Color television system with feedback control



June 27, 1967 M. MACAULAY COLOR TELEVISION SYSTEM WITH FEEDBACK CONTROL Filed Aug. 23, 1966 3 Sheets-Sheet l l I I I I I I I I I I I I I I Inu- INVENTOR. I M/ucoz Alarm/Ay June 27, 1967 M. MACAULAY COLOR TELEVISION SYSTEM WITH FEEDBACK CONTROL Filed Aug. 23, 196e INVENTOR. Mfucoz/f aow/Ay PIES l P Q Viana/frs June 27, 1967 M. MACAULAY 3,328,520

COLOR TELEVISION SYSTEM WTH FEEDBACK CONTROL Filed Aug. 23. 1966 5 Sheets-Sheet 3 PIES INVENTOR. Manu/v fymmmy from/sys United States Patent() 3,328,520 CLOR TELEVISION SYSTEM WITH FEEDBACK CONTROL Malcolm Macaulay, 2056 Summit Ave., St. Paul, Minn. 55105 Filed Aug. 23, 1966, Ser. No. 575,220 9 Claims. (Cl. 178-5.4)

ABSTRACT OF THE DISCLOSURE Repetitively grouped, orthogonally spaced phosphor regions are scanned by a single electron beam. Three closely adjacent phosphor regions constitute a group and each ldifferent phosphor region of a group is capable of producing a different primary color. An anode region confronts each phosphor region and by means of feedback circuitry the response signals derived from the acutal degree of impingement on any one, portions of any two or portions of all three phosphor regions of a group are compared with command signals representing Wh-at the degree of impingement should be. Correction, when needed, is accomplished by horizontally and vertically shifting the beam in the appropriate direction, although if only a horizontal of vertical shift is necessary, a shift in either of these directions is automatically achieved.

This invention relates generally to television systems, and pertains more particularly to a system for producing color pictures with a cathode ray tube having but a single electron gun therein.

Briey, my invention comprises a cathode ray tube including a luminescent screen having a multiplicity of individual, repetitively grouped regions containing phosphors capable of emitting red, blue and green light when struck by a stream of electrons generated by a single electron gun at the end of the cathode ray tube opposite the screen. The red phosphor underlies an anode in the form of a thin panel of electrically conductive material. The blue and green phosphors overlie transparent anodes in the form of panels of an electrically conductive material. The panels backing the red phosphor regions are joined together electrically, the panels confronting the blue phosphor regions are joined together electrically land the panels confronting the green phosphor regions likewise are electrically connected to each other. The various phosphor regions are arranged in a definite pattern and through the agency of a feedback circuit, the electron beam is constrained to strike the appropriate phosphor regions in a relatively precise manner by virtue of error signals derived from the anode currents that energize a supplementary deflecting means that results in the proper shift of the beam onto the correct region or regions, as the case may be, during the scanning process.

An important object of the invention is to provide a more precisely `delineated picture than heretofore via a feedback control that causes the electron beam to be shifted, when necessary, into a more accurate alignment with the particular phosphor region it should be striking at the moment. Stated somewhat differently, if the electron beam is not properly impinging upon the region that will produce the color called for in the signal received from the television transmitter, an error signal is generated which rapidly shifts the beam in the correct direction so that a true color is imparted to the image being displayed to the television viewer.

Another object of the present invention is to provide a color television system that will pos-Sess economic advantages over existing systems by reason of its over-all technical simplicity.

A more specific object is to provide a tricolor picture ICC tube that may be manufactured with low tooling costs. For instance, the picture tube utilized in accordance with the teachings of the instant invention requires no shadow mask which, because ofthe need for precise relative location with the viewing screen, requires extremely accurate manufacturing techniques. My system also obviates the need for indexing strips which have been used in certainprior art arrangements and which require special fabricating steps to be followed.

In achieving the simplified system herein disclosed, it is an aim to eliminate certain components that have heretofore been relied upon in order to provide an acceptable color picture. Included in this category are convergence yokes or electrodes or both. Also, in my system, the high voltage power supplies do not have to be closely regulated nor are high level color signal amplifiers required. These are but a few examples of the components that can either be `dispensed with or modified appreciably in order to produce a low cost system that will be reliable, economical and effective. f

A further object of the invention is to provide a color television system of the foregoing character that makes use of conventional components throughout and also assembly equipment currently in production use, although the manner in which such components are combined and coact is quite different. The color screen on the cathode ray tube is manufactured by circuit etching techniques, phosphor deposition methods, and screen aluminizing methods used in producing color television picture tubes presently being marketed.

Further, an object of my invention is to provide a color television system that is more eicient than those currently extant. By the elimination of the aperture mask, Iall the electrons leaving the electron gun are caused to fall on the screen rather than the mere 15 or 20% commonly obtained in aperture mask tubes. Unlike other single gun systems heretofore disclosed, my invention provides for the simultaneous sharing of the electron beam energy between the phosphors. Consequently, signal switching means are eliminated and dead time during switching intervals is avoided. The result of these advantages over other tricolor picture tubes currently being produced is a brighter image for a given electron beam energy.

Another object of my invention is to provide a color television receiver of compact dimensions. By eliminating the need for converging three electron beams, a shorter beam path may be employed with Wide deflection angles. A color television receiver made using the techinques of my invention will require no larger cabinet than a monochrome receiver of identical screen size.

Yet another object of the invention is toprovide a color television system that is relatively easy to adjust initially, and which when adjusted is not apt to get out of adjustment readily. Consequently, very little installation time is required and subsequent lservice calls are quite minimal.

These and other objects and advantages lof my invention will more fully appear from the following description, made in connection with the accompanying drawings, wherein like reference characters refer to the same or similar parts throughout the several views and in which:

FIGURE 1 is a perspective view of a cathode ray tube embodying my invention, the glass envelope thereof being indicated only in phantom outline, and the view including schematic circuitry which provides a feedback control for the electron beam;

FIGURE 2 is a greatly enlarged front elevational view of a fragmentary portion of the screen shown in FIGURE l, the enlarged scale allowing the phosphor regions and electrical connections to be shown to better advantage than in FIGURE 1;

FIGURE 3 is a sectional view taken generally in the 3 lirection of line 3-3 of FIGURE 2 for the purposeof howing the various panelvanodes and their relation to he phosphory regions and the interconnecting members; FIGURE 4 is a sectional view taken generally in the lirection of line 4 4 of FIGURE 2;

FIGURE 5 is still another sectional view, this view.

leing in the direction of line l5--5` of FIGURE 2, and

FIGURE 6 is a graph with the straight portion (dashes) howing how the horizontal displacement Vof the elecron beam is affected by the horizontal yoke current and Vith the stepped portion (solid) showing the resulting :ffect from the addition `of sawtooth pulses.

Referring now in detail to FIGURE l, the glass en- 'elope of the cathode ray tube has been indicated in )hantom outline by the numeral 10. At the neck end of the ube 10 is a conventional electron gun 12, it being im- )ortant to appreciate at the outset that only one such gun is employed in practicing my invention. The cathode `ay tube is also provided with a conventional electromagietic defiecting yoke having vertical and horizontaldelecting coils 13 and 14, respectively. A set of electro-V tatic deflecting plates 15a, 15b and 16a, 16b is profided to permit convenient supplementary deflection.

Although the above-mentioned components are confentional, the luminescent screen labeled 18 is decidedly lifferent. The screen 18, as more readily understood from t consideration of FIGURES 2 5, includesy a multiplicity if individual prosphor regions 20R, 20B and 20G ar- 'anged in a predetermined pattern which will become :learer as the description progresses, particularly in coniection with the ensuing operational sequence that will be )resented Various phosphor materials are available, so here is no need to detail the various compositions of the egions 20R, 20B and 20G other than to state that each iegion 20R emits light when excited'by the electron beam generated by the-gun 12, the regions 20B blue light andv vhe regions 20G green light.

The dimensions of the various repetitively grouped reions 20R, 20B'and 20G are related proportionately to v,he image size of the picture tube, One region 20B, one egion 20G and the section of the region 20R therebeieath form one group (the red phosphor strip need not Je continuous as long as the sections are electrically conlected as will later become apparent). For a picture tube lVith an image diagonal dimension of 13 inches, for eximple, the lheight of each reigon may be considered to Je on the order of 0.015 inch. The width of the regions 20B and 20G may be of the order of 0.012 inch, whereas :he region 20R, being illustratedas a strip in each instance, has a width equal to the combined widths of the egions 20B, 20G plus the spacing therebetween. The spacing between the regions 20B and 20G, as well as be- '.ween those regions and the region 20R therebeneath, approximates 0.001 inch. Under these` circumstances, the iiameter of the electron `beam. should not be greater than ).014 inch (the width of one individual region 20B or 20G plus the spacing t-o each side thereof) so that when :he beam is centered horizontally on a phosphor region, there will be no overlap onto the next adjacent phosphor region. In other words, if only, say, blue is called' for and the electron beam is accurately impinging on a phosphor region 20B, there should under these circumstancesv be no striking of any other phosphor region which would degrade the color balance. `Of course, with my system, the beam can be shifted to strike portions of all three phosphor regions 20B, 20G and 20R of a group when commanded to do so in orderto present a picture having the requisite color balance.

As ibest shown in the sectional view of FIGURE 4, each region 20R has a backing reflecting land or panel 22R which functions as an anode, the-panel being suggestively of aluminum, the panel being substantially co. extensive with its underlying phosphor material constituting the region 20R. The regions 20B each have a confronting transparent land or panel 22B, FIGURES 3 and 5, functioning collectively as aditional anodes, the panels being suggestively of tin oxide. Similarly, the regions 20G each have a land or panel 22G, illustrated sectionally in FIGURES 3 and 5, functioning as still other anodes.

The panels 22R are most readily connected together at one end as indicated by the strip 23, in FIGURE 2. However, the panels 22Bv are joined by electrically conductive strips 24 and the panels 22G by strips 26 as is alsok apparent from FIGURE 2. It should be understood at this time that the various panels 22R, 22B and 22G are not interconnected electrically, being instead insulated or isolated from each other.

It might be helpful to outline `one Way that the screen 18 can be produced. The tin oxide yforming the panels 22B and 22G is first appliedto the glass face of the envelope 10 by vapor deposition through a stencil, or by photoetching away the excess material of an over-all evaporated coating. Next, a thin layer of aluminum is evaporated over the surface followed by an etching step to remove all but the bridging or connecting strips 24, 26. Since typical phosphors have insulating properties, it is not essential that the strips 24, 26 be electrically yinsulated from the overlying phosphor region 20R, yet to be applied, but for assurances sake, the strips may be oxidized to give an insulating characteristic. When the several phosphor regions 20R, 20B and 20G are applied, as by silk screening, .the partially completed screen is in readiness for the panels 22R which panels are applied over the phosphor `region 20R by vapor deposition through a stencil. At this stage, it will be recognized that, in effect, three separate color phosphor associated anode patterns have been produced which are not electrically connected with each other. Stated somewhat differently, the screen 18 has been completed without electrically interconnecting the regions 20R, 20B and 20G.

At this time, it 4will be convenient to consider the electrical -circuitry illustrated in FIGURE 1.,Atelevision receiver has been designated generally by the reference numeral 30. Within the receiver 30 is a signal source 32. which may comprise such components as the antenna, tuner, radio-frequency amplifiers,r converter, intermediate frequency amplifiers and video detector. The output from the signal source 32 is processed, being a composite signal, via various electrical paths. One such path includes a 'luminance amplifier 34 which .in turn is connected to the control grid of the electron gun 12. Another electrical path includes color demodulation circuits collectively indicated by the referencenumeral 36, these circuits providing individual output signals at 38R, 38B and 38G. Thus, the signals provided at outputs 3BR, 38B and 38G are indicative or representative of the amount of red, blue.

and green color, respectively, that should appear in the ultimate picture `formed on the screen 18. Stated somewhat differently, the signals provided at 38R, 38B and 38G are command voltages designating what the color strengths should be.

Another electrical path from the signal source 32 in- -cludes a sync separator 40 which. in turn is connected to the vertical deflection control circuit 44 and the horizontal deflection control circuit 42. It is these circuits 42 and 44 that energize the coils 14 and 13.

Still another electrical path `derived from the signal source 32 involves a sawtooth pulse generator 46 for the purpose of causing the electron beam to ju-mp to successive positions on the various regions 20B and 20G as will be presently explained. The generator 46 in the form of a multivibrator is driven from the 3.58 megacycle color subcarrier oscillator which is conventional in the color sync circuits 33 of receiver 30. The alluded-to frequency is a standard frequency utilized during the transmissiony of television signals in order to synchronize the color demodulators at the receiving end. More will be said later concerning the speci-fic role played by the pulse generator 46. At this time, it will beappreciated that the system herein described is compatible `with the standards for commercial broadcast television that have been adopted and are currently used in the United States.

At this time, attention is directed to means for comparing the color command signals forwarded via the outputs 38R, 38B and 38G with voltage signals described immediately below. To furnish these additional signals, there are conductors 50R, 50B and 50G connected to conductive strips 23, 24 and 26 extending from the panels or anodes 22R, 22B and 22G, respectively. The conductor SOR is connected to the error detector 48R, the conductor 50B to the error detector 48B and the conductor 50G to the error detector 48G. Also, it is noted that high voltage terminals SZR, 52B and 52G are provided. These terminals apply high voltage potentials to the various anode panels 22R, 22B and 22G. It should be plain at this moment, though, that the supply potentials -need not be the same in each instance and preferably are selected to give the best operation. At any rate, there are resistors 54R, 54B and 54G connected between the terminals SZR, 52B and 52G, respectively, and the several conductors SOR, 50B and 50G, respectively. These resistors 54R, 54B and 54G are in the anode return circuit and therefore the voltage drops across them will provide representations of the degree of impingement of the beam and therefore a measure of the amount of light then bei-ng emitted from the associated regions R, 20B and ZGG of screen 18. It will sufiice for the moment to point out that the voltage forwarded from the output 3BR is compared with `the voltage provided via the `conductor 50R. The error detector 48R then develops a signal that can be used to correct the position of the electron beam. The output from the error detector has been assigned the reference numeral 56R. Similarly, the outputs from the error detectors 48B and 48G have been given the reference characters 56B and 56G, respectively.

The several error signals 56K, 56B and 56G are employed for controlling supplementary deflecting means comprised of the previously-mentioned horizontal deection plates 15a, 15b and the vertical deflection plates 16a, 1Gb. The output 56R is connected to the vertical defiection plate 16a through amplifier 62; the other vertical deflection plate 16b is connected to ground. The outputs 56B, 56G are connected to the horizontal deflection plates 15a, 15b through amplifiers 66y and 68. The amplified signal from the amplifier 66 is connected directly to the horizontal deection plate 15a. On the other hand, the output from the amplifier 68 is connected to one input of a summing amplifier which has been given the reference numeral 70. The second input to the summing amplifier 70 is derived from pulse generator 46. The output of summing amplifier 70 is then applied to the other horizontal deflection plate 15b.

The interaction of the components mentioned above may be understood from a typical operating sequence. First, for purposes of explanation only, consider the electron beam stationary at various positions as shown in FIGURE 2. If the color picture signal being processed by the receiver calls for only red at a given instant, command Voltage 38R will be a maximum. Considering the effects at screen 18, the electron beam position indicated at A in FIGURE 2 will cause what might be termed pure red light to be emitted with a high value of current iiow in the red electrode circuit which includes the resistor 54R and the conductor SUR. The high current flow through the resistor 54R will cause a correspondingly high voltage drop to occur across the resistor S4R. Thus, a large signal is delivered to the error detector 48R. Assuming that the circuit components have proper calibrations, the voltage SOR will match the voltage 3SR, so no error voltage 56R will be produced. Similarly, the electron beam displayed in the position B will cause pure blue light to be emitted and current to flow in the blue electrode circuit. Here again, no error signal will be produced from the error detector 48B if command voltage 38B .is a maximum, and no supplementary deflection signal will he applied to the horizontal deflection plate 15a. The beam in position C will cause pure green light to be emitted and the current flow in the green electrode circuit will cause no potential to be applied to the horizontal deflection plate 15b. However, a different situation is indicated by the position D in -FIGURE 2. In this situation, the electron beam will cause a colored light of a hue determined by the proportion of red, green and blue light emitted by the severa-l phosphor regions 20R, 20B and 20G which are simultaneously struck by the beam in this instance. The currents owing in the several anode circuits will deliver signals to the several comparison means or error detectors 48R, 48B and 48G that, by offsetting the command signals SSR, 38B and 3-SG, will retain the electron beam in this particular position D. Stated somewhat differently, there will be an appropriate signal provided that will cause the electron beam li-terally to straddle the phosphor regions 20R, 20B and 20G, thus proportionately dividing its energy to cause the commanded color of light to be emitted from screen 18.

As shown in FIGURE 2, during dynamic operation, the electron beam scans from right to left under the control of the horizontal deection circuit 42 as indicated by the arrow 72 (since the view is in the direction of electron movement from the gun 12 to the screen 18), this being the conventional fashion and from top to bottom under -the contr-ol of the vertical deflection circuit 44 in an interlaced manner, as is also conventional. It may be seen that certain locations, named nominal chroma centers, are vdesignated E1, E2, E3, F1, F2 and F3. These positions are topologically unique since red phosphor region 20R Ylies immediately below, blue phosphor region 20B lies above and to the left and green phosphor region 20G lies above and to the right. Small deflections of the electron beam from these positions E1, E2, E3, F1, F2 and F3 can be made to provide any color of light capable of being emitted by the phosphors singly or in combination. The vertical positi-on of the beam is a consequence of the conventional vertical deiiection signals from vertical deflection circuit 44 through the agency of vertical deflection coil 14 and the supplementary vertical deflection signals from amplifier 62 impressed on vertical deflection plate 16a. Since phosphor region 2BR lies everywhere below a scan path line such as 72 through nominal chroma centers El, E2 and E3, the red color content of the image being gene-rated may be c-ontinuously sensed and the vertical position of the beam corrected as the horizontal scan proceeds. However, the movement of the beam in a horizontal direction from position E2 to position E3, for example, must be made in such fashion as to avoid light generation when the beam does not strike the phosphor regions 20B and 20G so as to yield the correct proportions of blue and green light. Therefore, the beam is caused to move Ior shift rapidly between the positions of correct blue and green light generation proportion about nominal chroma centers. By virtue of -the velocity of the beam during these rapid excursions, little unwanted light is generated. The rapid motion is caused by sawtooth pulses from pulse generator 46 acting through the summing amplifier 70 and horizontal ldeflecting plate 15b.

A more complete understanding of the beam travel details may be gained by referring to FIGURE 6. FIGURE 6 isa graph representing in one instance the horizontal displacement lof the electron beam due only to the action yof the horizontal deiiection yoke current. The displacement is indicated in terms of nominal chroma center positions labeled El-EN at the time of saw tooth pulse rising wavefront occurrences. As shown by the dashed or broken line 74, the beam will sweep linearly at a constante rate if it is under the influence of the yoke current only. FIG- URE 6 also graphically depicts the displacement of lthe electron beam due to the electric field at the deflecting plates 15a, 15b that resul-ts from the sawtooth pulses added by the generator 46, the combined or total effect being indicated by the solid line 76. As shown, the effect if this lield is to cause the beam to jump an incremental listance between nominal chroma centers. Error signals which would vary anyway) are omitted in order to keep he representations 74, 76 basically simple in appearance.

The horizontal position of the beam is thus the conse- {uence of the combination of the horizontal deliection ignals from conventional horizontal deflection circuit l2 through the agency of horizontal deflection coil 14, he supplementary horizontal deflection signals from tmplilier 66 impressed on horizontal deliection plate lSa and theisawtooth pulses from pulse generator 46 :ombined by means of summing amplifier 70 with the `upplementary horizontal deflection signal from ampliier 68 and impressed on horizontal deflection plate 15b. Irom the operational description that has been presented, t will be appreciated that the electron beam, even though generated by a single gun 12, is brought more nearly into )roper alignment with the particular region ZR, B or BOG or a combination thereof, so as to provide an overlll color balance in the picture displayed on screen 18 inder dynamic conditions.

It will, of course, be understood that various changes nay be made in the form, details, arrangements and pro- Jortions of the parts without departing from the scope of ny invention as set forth in the appended claims.

I claim:

1. In a television system responsive to color picture zignals,

means for generating a single beam of electrons,

atluminescent screen including respectively grounded iirst, second and third phosphor regions capable of producing first, second and third colors, respectively, when struck by said electron beam, lthe first phosphor region of each group being .spaced vertically with respect to the second phosphor region and the third phosphor region being spaced horizontally with respect to the first phosphor region,

means for deliecting said electron beam horizontally and vertically to cause said beam to scan the grouped regions in sequence,

first electrical means in electrical contact with only the first phosphor region for providing an electrical response signal Arepresentative of the vdegree of impingement of said beam on said iirst phosphor region,

second electrical means in electrical contact with only the second phosphor region for providing an electrical response signal representative of the degree of impingementof said beam on said second phosphor region,

third electrical means in electrical contact with only the third phosphor region for providing an electrical response signal representative of the degree of impingement of said beam on said third phosphor region,

means for providing separate electrical command signals which specify the degree to which said beam should impinge upon said phosphor regions,

means for comparing said response signals with said command signals to produce correction signals related to the differences between the commanded degree of impingement and the actual degree of impingement, and

means responsive to said correction signals for horizontally and vertically shifting said beam when needed to cause the actual degree of impingementto correspond substantially Ito said commanded degree of impingement as said beam scans said repetitively grouped phosphor regions.

2. In a television system responsive to color picture signals,

an electron gun for generating a single beam of electrons,

a luminescent screen having a plurality of repetitively grouped first, second and third phosphor regions f5 capable of producing first, second and third colors, respectively, when struck by said beam, the lirst phosphor region of each group being spaced vertically with respect to the second phosphor region and the third phosphor region being spaced horizontally with respect to the first phosphor region,

means for deliecting said electron beam horizontally and vertically to cause said beam to scan the grouped regions in sequence,

an anode region associated with each of said phosphor regions so thaty said electron beam striking any individual phosphor region will produce an electrical response signal in the anode region'associated with that individual phosphor region,

first means electrically connecting together the anode regions associated with said firstphosphor regions,

second means electrically connecting together the anode regions associated with said second phosphor regions,

third means electrically connecting together the anode regions associated with said third phosphor regions,

means having a first output providing an electrical command signal representative of the degree to which said beam should impinge upon said first phosphor regions, a second output providing an electrical corn-v mand signal representative of the degree to which said beam should impinge upon said second phosphor regions, and a third `output providing an electrical command signal representative of the degree to which said beam should impinge upon saidthird phosphor regions,

a first comparison-means in circuit with said first connecting means and the first output of said command signal means for comparing the electrical response signal derived from said first phosphor regions with the command signal from said first output to provide a first correction signal representative of any difference between said rst phosphor response signaland said first output command signal,

a second comparison means in circuit with said second connecting means and the second output of said command signal means for comparing the electrical response signal derived from said second phosphor regions with the command signal from said second output to provide a second correction signal representative of any difference between said second phosphor response signal and said secondoutput command signal,

a third comparison means in circuit with said third connecting means and the output of said command signal means for comparing the electrical response signal derived from said third phosphor regions with the command signal from said third output to provide a third correction signal representative of any differences between said third phosphor response signal and said third output command signal, and

means responsive to said correction signals for horizontally and vertically shifting said electron :beam to cause the degree of impingement of said beam on said first, second and third phosphor regions to correspond substantially to the commanded degree of impingement as called for by said first, second and third command signals as said beam scans said repetitively grouped phosphor regions.

3. A television system in accordance with claim 2 in which each of said first, second and third electrically connecting means provides an anode return circuit and each has a resistor therein whereby the voltage drops across said resistors are representative of the degree of beam impingement on the first, second and third phosphor regions.

4. A television system in accordance with claim 2 in Awhich the anodes for the first and second phosphor regions are optically transparent and confront the sides of said first and second phosphor regions remote from said gun, and

said anodes for the third phosphor regions confront the sides of said third phosphor regions nearer said gun.

5. A television system in accordance with claim 2 in which said horizontal and vertical deilecting means includes an electromagnetic deilecting yoke having vertical and horizontal deecting coils,

a vertical dellection circuit for said vertical dellecting coils,

a horizontal deilection circuit for said horizontal deecting coils, and

in which said last-mentioned means includes supplemental electrostatic vertical and horizontal deflecting plates to which said correction signals are applied to shift said electron beam in the direction of commanded impingement.

6. A television system in accordance with claim 5 in which said rst and second phosphor regions are alternately arrange in spaced horizontal rows and said third phosphor regions are arranged in horizontal rows therebetween,

said iirst and second correction signals being applied to said horizontal deecting plates and said third correction signal being applied to one of said Vertical defiecting plates,

a sawtooth pulse generator, and

a summing amplifier having one input connected to said sawtooth generator and a second input connected to the output of said second comparison means so that said second correction signal and the signal from said generator are summed,

the summed signal from said summing amplier being applied to one of said horizontal deflecting plates,

whereby said electron beam when shifted horizontally is caused to jump to successive horizontal positions relative to said first and second phosphor regions.

7. In a television system responsive to color picture signals,

means for generating a single Ibeam of electrons having a given diameter,

a luminescent screen having first, second and third phosphor regions capable of producing rst, second and third colors, respectively, when struck by said beam, said phosphor regions constituting a group and said group being repeated so as to provide a plurality of groups each containing a rst, second and third phosphor region, the first phosphor region of each group being spaced vertically with respect to the second phosphor region and the third phosphor region being spaced horizontally with respect to the first phosphor region,

the phosphor regions of each group Ibeing spaced from each other a distance less than the diameter of said beam so that said beam can simultaneously strike portions of the iirst, second and third phosphor regions of any one of said groups,

a irst anode region confronting each rst phosphor region but not any of said second and third phosphor regions so that any portion of said electron beam striking a rst phosphor region will produce a fir-st electrical response signal having a magnitude in accordance with the degree of beam impingement thereon,

a second anode region confronting each second phosl0 phor region but not any of said first and third phosphor regions so that any portion of said electron beam striking a second phosphor region will produce a second electrical response signal having a magnitude in accordance with the degree of impingement thereon,

a third anode region confronting each third phosphor region but not any of said rst and third phosphor regions so that any portion of said electron beam striking a third phosphor region will produce a third electrical response signal having a magnitude in accordance with the degree of beam impingement thereon,

circuit means connecting only the rst anodes together,

circuit means connecting only the second anodes together,

circuit means connecting only the third anodes together,

means providing rst, second and third electrical command signals having respective magnitudes representative of the degree said beam should strike the phosphor regions of any one group at a particular moment,

rst mean-s for comparing said Iirst response and command signals to provide a rst correction signal in accordance with any dilference in magnitude therebetween,

second means for comparing said second response and command signals to provide a second correction signal in accordance with any dilerence therebetween,

third means for comparing said third response and command signals to provide a third correction signal in accordance with any difference therebetween,

means for deilecting said electron beam in a direction to scan said groups of phosphor regions, and

means responsive to said rst, second land third correction signals for horizontally and vertically shifting said electron beam suiciently to correspond substantially to the commanded degree of impingement as called for by said rst, second and third command signals.

8. A television system in accordance with claim 7 in which said rst and second phosphor regions of said various groups are arranged in horizontal parallel rows with said third phosphor regions arranged in horizontal parallel rows therebetween,

the diameter of said beam being no greater than the width of an individual rst or second phosphor region plus the width of the spacing to each side thereof.

9. A television system in accordance with claim 7 including means associated with said last-mentioned means for causing said beam to jump rapidly from group to group in the direction of horizontal scan provided by said detlecting means when said beam is shifted horizontally.

References Cited UNITED STATES PATENTS 2,700,697 1/ 1955 Houghton 178-5.4 2,706,216 4/1955 Lesti 178-5.4 2,977,408 3/ 1961 Welch 178-5.4 3,146,369 8/1964 Kaplan 313-92 DAVID G. REDINBAUGH, Primary Examiner.

I. A. OBRIEN, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE 0F CORRECTION Patent No 3 ,328 ,520 June 27 l967 Malcolm Macaulay It is hereby certified thatJ error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column l, line 8, for "acutal" read actual line 14, for "of" read or column 2, line 7, for "certain" read certain line 48, for "technques" read teachings line 69, after "and" insert their column 3, line Z8, for "prosphor" read phosphor line 35, after "emits" insert red line 46, for "reigon" read region column 6, line 67, for "saw tooth" read sawtooth line 69, for "constante" read constant column 7, line 30, for "respectively grounded" read repetitively grouped column 9, line Z3, for "arrange" read arranged (SEAL) Signed and sealed thls 6th day of August 1968 Attest:

Edward M. Fletcher, Jr. EDWARD J. BRENNER Attesting Officer Commissioner of Patents 

1. IN A TELEVISION SYSTEM RESPONSIVE TO COLOR PICTURE SIGNALS, MEANS FOR GENERATING A SINGLE BEAM OF ELECTRONS, A LUMINESCENT SCREEN INCLUDING RESPECTIVELY GROUNDED FIRST, SECOND AND THIRD PHOSPHOR REGIONS CAPABLE OF PRODUCING FIRST, SECOND AND THIRD COLORS, RESPECTIVELY, WHEN STRUCK BY SAID ELECTRON BEAM, THE FIRST PHOSPHOR REGION OF EACH GROUP BEING SPACED VERTICALLY WITH RESPECT TO THE SECOND PHOSPHOR REGION AND THE THIRD PHOSPHOR REGION BEING SPACED HORIZONTALLY WITH RESPECT TO THE FIRST PHOSPHOR REGION, MEANS FOR DEFLECTING SAID ELECTRON BEAM HORIZONTALLY AND VERTICALLY TO CAUSE SAID BEAM TO SCAN THE GROUPED REGIONS IN SEQUENCE, FIRST ELECTRICAL MEANS IN ELECTRICAL CONTACT WITH ONLY THE FIRST PHOSPHOR REGION FOR PROVIDING AN ELECTRICAL RESPONSE SIGNAL REPRESENTATIVE OF THE DEGREE OF IMPINGEMENT OF SAID BEAM ON SAID FIRST PHOSPHOR REGION, SECOND ELECTRICAL MEANS IN ELECTRICAL CONTACT WITH ONLY THE SECOND PHOSPHOR REGION FOR PROVIDING AN ELECTRICAL RESPONSE SIGNAL REPRESENTATIVE OF THE DEGREE OF IMPINGEMENT OF SAID BEAM ON SAID SECOND PHOSPHOR REGION, 